Protons
Electrons
Bronsted Lowry acids/bases associated with ______ while Lewis acids/bases are associated with ______.
Donors; protons
Acids are _____ (donors/acceptors) and give off _____
Acceptors; protons
Bases are _____ (donors/acceptors) and accept _____
True
T/F - If some molecule has lone pair of electrons or negative charge it can accept protons, thus acting like a base
acceptors
donors
Lewis acids are electron-pair _______ and Lewis bases are electron-pair _____
coordinate covalent
Lewis/acid base reactions are involved in formation of __________ bonds
After it donates a proton (H+)
When does a Bronsted Lowry acid turn into its conjugate base?
conjugate acid
When a bronsted lowry base accepts a proton, what is the product? (conjugate base or acid)
the base is missing a proton (H+)
What is the difference between the bronsted acid and its conjugate base?
the acid has an extra proton (H+)
What is the difference between the bronsted base and its conjugate acid?
Answer: C
Bronsted lowry acid donates a proton (H+) while a lewis acid accepts electrons. B. L acid must have an H to give
Which of the following can behave as a Bronsted Lowry acid but not a Lewis acid?
A. CF4
B. NaAlCl4
C. HF
D. Br2
Answer D
What is the conjugate base of HBrO (hypobromous acid)?
A. H+
B. H2BrO2
C. H2BrO+
D. BrO-
depends on how completely it ionizes in water
What determines if an acid is strong or weak?
when it dissociates completely in water
What makes a strong acid?
Weak acid does not have a complete dissociation in water. Strong acids do.
What is the difference between strong and weak acid?
related to how much the products are favored over the reactants
How is the strength of an acid expressed?
False: It would be a strong acid since the reactants almost completely dissolved in water.
T/F- If there are 99% products and 1% reactants, the acid is considered weak
Ka = Acid ionization (acid dissociation) constant
Keq = equilibrium constant
What does Ka mean relative to Keq?
stronger
smaller
The larger the Ka, the _____ the acid and the _____ the Ka, the weaker the acid
Ka > 1 for strong acids
Ka < 1 for weak acids
Ka = ? to be a strong acid
Ka = ? to be a weak acid
HI, HCl, HBr, HClO4, H2SO4 and HNO3
List the common strong acids
A. weak acid
B. Strong acid
C. Strong acid
D. Weak acid
Strong or weak acid?
A. HF
B. HCl
C. HNO3
D. Acetic acid
False; they are strong acids
T/F - H2SO4 and HClO4 are considered weak acids
Answer A
Very low Ka means a very weak acid and reaction will favor reactants and not products
In a 1M aqueous solution of boric acid (H3BO3 Ka = 5.8 x 10^-10) which of the following species will be present in solution in the greatest quantity?
A. H3BO3
B. H2BO3 -
C. HBO3 2-
D. H3O+
F- has a smaller radius than Cl-, Br- and I-
Why is HF a weak acid but HCl, HBr, and HI are strong acids?
It is a strong acid
If an acid's conjugate base is stable, what does this say about the acid?
stable
The larger the radius, the more _____ the conjugate base.
Answer: D, HF is a weak acid
which is a weak acid?
A. HCl
B. HBr
C. HI
D. HF
Base-ionization, base-dissociation constant
What does Kb mean?
stronger
smaller
The larger the Kb, the _____ the base and the _____ the Kb, the weaker the base
Strong base
Strong or weak base?
Group 1 hydroxides (i.e NaOH)
Weak base
Strong or weak base?
Ammonia (NH3)
Weak base
Strong or weak base?
Amines
Strong base
Strong or weak base?
Group 1 oxides (i.e Li2O)
Answer: B
Which group oxides are considered strong bases?
A. Ca(OH)2)
B. Mg(OH)2)
C. Sr(OH)2)
D. Ba(OH)2)
False
they are strong bases
T/F - metal amides (i.e: NaNH2) are considered weak bases
weak
Conjugate bases of weak acids are _____ bases
strong
no
The conjugate base of a _____ acid has _____ (some/no/all) basic properties in water
False
Because HCl is a strong acid, its conjugate base does NOT have any basic properties
T/F - HCl has a conjugate base with some basic properties
True
HF is a weak acid therefore its conjugate base will have some basic properties
T/F - HF has a conjugate base with some basic properties
acid
weak
The conjugate base of a weak ______ is a _____ base
stronger
The weaker the acid, the ______ (stronger/weaker) the conjugate base
True
T/F - The conjugate acid of a weak base does not have acidic properties
weak; weak
weaker
The conjugate acid of a ____ base is a _____ acid. The ______ (weaker/stronger) the base, the stronger the conjugate acid
Answer: B
Can also think about it as "which is the weakest conjugate acid?"
A,C and D are all strong acids and HCN is a weak acid, therefore the weakest conjugate acid (strongest base)
Of the following anions, which is the strongest base?
A. I-
B. CN-
C. NO3-
D. Br-
Answer: A
Can also think about it as "which is the strongest acid?"
the only strong acid listed is HClO4; all the others are weak acids
Which of the following is the weakest conjugate base?
A. HClO4
B. HCOOH
C. H3PO4
D. H2CO3
Polyprotic acid
has more than one proton to donate
Amphoteric
- when a substance can act as either an acid or a base
base; amphoteric
The conjugate ______ of a polyprotic acid will always be _____ because it can either donate or accept another proton
It is Amphoteric
What is special about water as an acid? as a base
1.0 x 10^-14
The self-ionization (autoionization) of water has a Kw that equals to ______.
Increase in H3O+ ions and decreased in OH- ions since equilibrium is established at Kw = 1.0 x 10^-14
If an acid is introduced, what happens to the H3O+ ions and the OH- ions?
H3O+ ions
What kind of ions does pH measure?
pH = - log (H3O+)
[H3O+] = 10^-pH
What are the two equations related to pH?
Acidic solution = pH<7
Basic solution = pH>7
[H3O+] > 10^-7 = ______________
[H3O+] < 10^-7 = _____________
[H3O+] = 10^-7 is neutral
more
high
A low pH means a (more/less) _______ [H3O+] in solution and a ______ (low/high) pH means less [H3O+] in solution
acidic
less than
There is [H3O+] = 10^-5 in solution. The solution is ______ (basic/acidic) because its pH is ____ 7.
basic
greater than
There is [H3O+] = 10^-10 in solution. The solution is ______ (basic/acidic) because its pH is ____ 7.
OH-
pOH measure ______ ions
pOH = -log (OH)
[OH-] = 10^-pOH
What are the two formulas associated with pOH?
H3O+
lower
The greater the concentration of _____ ions, the _____ the concentration of OH- ions
...
What is the relationship between pH and pOH?
[H+] = y x 10^-n where:
- n = whole number
- y = not a whole number
**
the pH will be between (n-1) and (n)
**
How do you calculate pH if the [H+] is not a whole number?
high Ka
low pKa
A strong acid has a ____ Ka and a _____ pKa.
low Ka
high pKa
A strong base has a ____ Ka and a _____ pKa
Kw = Ka x Kb = 1.0 x 10^-14
Relate the strength of an acid and its conjugate base
What is the relationship between any acid-base conjugate pair using Ka and Kb? What information do we receive?
Kw = Ka x Kb = 1.0 x 10^-14
and
pKa + pKb = 14
What are two equations that show the relationship between an acid-base conjugate pair?
Answer: C
Low [H3O+] ions = High [OH-] ions = basic solution = high pH value
Which liquid contains the lowest [H3O+] ions?
A. Lemon juice pH = 2.3
B. Blood pH = 7.4
C. Seawater pH = 8.5
D. Coffee pH = 5.1
Answer: A
Le Chatelier's principle problem
Equilibrium is at 25 degrees celsius but the problem says this reaction occurs at 50 degrees celsius which means an increase in temperature. For an endothermic reaction, an increase in temperature means the react
***** The self ionization of water is endothermic. What is the value of the sum of pH+pOH at 50 degrees celsius?
H2O + H2O <--> H3O+ + OH-
A. less than 14
B. Equal to 14
C. Greater than 14
D. Cannot be determined
pH
The hydrogen ion concentration for a strong acid can allow you to calculate what directly?
ICE box and equilibrium expression
When you are given a weak acid with its concentration and you need to find the pH, which method would you use to find the answer?
when the Ka < 10^-4
When can you use the negligibility rule to find the pH of a weak acid?
Neutralization
salt and water
When an acid and base react together, this forms a _______ reaction and produces _______ and ________.
neutral
pH = 7
If there are equal amounts of strong base and stron acid in a neutralization reaction, what is the pH?
No
has to be equal amounts of strong base and acid reacting
Is the pH neutral (pH = 7) if there is a weak acid or base and a strong acid or base?
a x [A] x Va = b x [B] x Vb
a = # of acidic hydrogens per formula unit
b = constant; how many H+ ions the base can accept
What formula do you use if you are trying to figure out how much base (or acid) is needed in a solution for complete neutralization?
Answer D
Regardless of the strengths of the acids and bases, all neutralization reactions go to completion
Binary mixtures of equal moles of which of the following acid-base combinations will lead to a complete (99%) neutralization reaction?
I. HCl and NaOH
II. HF and NH3
III. HNO3 and NaHCO3
A. I only
B. I and II only
C. II and III only
D. I, II and III
false!
T/F - the strength of the acid and base is influences whether or not a neutralization reaction will go to completion
Cation and Anion
A salt contains which two substances?
stronger
NH4+
Be2+
Cu2+
Zn2+
Al3+
Cr3+
Fe3+
The cation in the salt will dissociate if it is a ______ acid than water. Some examples of these are_____
Groups 1 or 2
The cation in the salt will not react with water if it is a Group _____ or _____ cation
base
strong
The anion of a salt will not react with water if it is the conjugate ______ of a ______ acid
stronger
weak
The anion of a salt will dissociate in water if it is a _____ base than water. An example includes a conjugate base of a _____ acid
Answer: B
ClO- is the conjugate base of a weak acid. The solution will be basic
Which of the following salts will produce a basic solution when added to pure water?
A. KCl
B. NaClO
C. NH4Cl
D. MgBr2
Answer: C
Cu2+ is a stronger acid than water so CuCl2 is an acidic salt
Which of the following is an acidic salt?
A. KNO3
B. SrCl2
C. CuCl2
D. Ba(CH3COO)2
A solution that resists changing pH when a small amount of acid or base is added
What is a buffer?
Weak acid or base and its conjugate base or acid
What is present in a buffer?
It has enough base to neutralize the acid (or vice versa)
Why doesn't the pH rise drastically in a buffer solution?
Henderson-Hasselbalch Equation
an equation used in buffering solutions
[weak acid] = [conjugate base] so that pH = pKa
a weak acid whose pKa is close to the desire pH
What is considered a good buffer?
false!
choose a weak base and salt of its conjugate acid!
no strong bases
T/F - Another buffer solution can be formed by choosing a weak or strong base (and a salt of its conjugate acid) so that the pKb is close to the desired pOH
Answer: C
HCN is a weak acid
Look for a salt of its conjugate base
Which of the following compounds could be added to a solution of HCN to create a buffer?
A. HNO3
B. CaCl2
C. NaCN
D. KOH
hydrogen ions will be reacted with conjugate base
conjugate base will decrease and undissociated acid will increase in solution
For concept see pg. 246
As Hydrogen ions are added to an acidic buffer, what happens to the concentration of undissociated acid and conjugate base?
The base reacts with the hydrogen ions
so the base decreases and the conjugate acid increases
As hydrogen ions are added to a basic buffer solution, what happens to the concentrations of base and conjugate acid
Indicator
A weak acid that undergoes a color change when it is converted to its conjugate base
According to the Le Chatelier principle the indicator's equilibrium would shift to the left, and the indicator would display color #1
What if an indicator were added to an acidic solution, whose pH were quite low due to a high concentration of H3O+ ions?
the amount of H3O+ ions would decrease
The indicator's equilibrium would be shifted to the right causing to display color #2
What if an indicator were added to a basic solution, whose pH were quite high due to a high concentration of OH- ions?
[HA] >>> [A-] therefore we would see color #1
If [H3O+] >>> Ka, which color would we see?
[HA] = [A-] therefore we would see a mix of color #1 and color #2
If [H3O+] = Ka, which color would we see?
[HA] <<< [A-] therefore we would see color #2
If [H3O+] <<< Ka, which color would we see?
pKa +/- 1
What is the general rule for pka and indicators?
to determine:
1. the identity of an unknown weak acid or weak base by determining its pKa or pKb
2. concentration of any acid or base solution (whether known or unknown)
What is the purpose of an acid/base titration?
Strong acid or base
Titrant (opposite of whatever was added above)
What is added in a titration?
False!
One never titrates an acid with an acid or a base with a base.
T/F: some titrations are acid-acid or base-base
Half equivalence point
Buffering region
Equivalence point
List the basic characteristics of a titration graph
Below pH 7
As you add more strong base then the pH will slowly increase
If a strong base is the titrant and you start with a weak acid, where will the pH start - above or below pH = 7?
Buffering region
the section of the titration curve where the pH changes very gradually
Equivalence point
Which region of the graph causes a drastic increase in pH?
moles of OH- added is equal to the moles H+ initially present.
Just enough titrant has been added to completely neutralize all the acid or base
What does the equivalence point mean?
pH > 7
For a weak acid (titrated with a strong base), where will the equivalence point occur?
False - pH < 7
T/F - For a weak base (titrated with a strong acid), the equivalence point will occur pH > 7.
Answer: B
Where the equivalence point occur for a strong acid titrated with a strong base or a strong base titrated with a strong acid?
A. pH < 7
B. pH = 7
C. pH > 7
The solution consists of equal concentrations of weak acid and its conjugate base OR weak base and its conjugate acid
[HA] = [A-]
What is in solution when the titration reaches half equivalence point?
pH = pKa because [HA] = [A-] and log 1 = 0.
When the solution is at half equivalence point, what does this mean for pH and pKa according to the Henderson-Hasselbach equation?
7
For strong acid and strong base, the pH is equal to ____ at equivalence point.
The number of ionizable hydrogens an acid can donate
How many equivalence points are seen in a titration graph for a polyprotic acid?
Answer D
Methyl red changes color in acidic pH values. Therefore, a titration with an equivalence point with pH > 7 means a weak base titrated with a strong acid.
Methyl red is an indicator that changes from red to yellow in the pH range 4.4-6.2. For which of the following titrations would methyl red be useful for indicating the equivalence point?
A) HCN titrated with KOH
B) NaOH titrated with HI
C) Benzoic acid ti